How to find cube root using while loop?

In the attached document, how would you write a while loop to display the cube root as it asks. Im more familiar with for loops, so is the while loop the same way? Im just confused how to output the cube root. Im starting off with input statements; not sure if im on the right track?

[Jaideep Dudi]

Cube root command

[Walter Roberson]

There is no cube root command in MATLAB.

x.^(1/3)
nthroot(x, 3)  %x must be real
pow(x, 1/3)
exp(log(x)/3)

For negative x, all of the above are identical except for nthroot. For positive x, the mathematical model for all of them is as-if exp of log had been used, but MATLAB is allowed to detect that an integer root is being taken and potentially use an alternative code path.

Answer 1

[Walter Roberson]

for K = 1 : 5
   something
end

is nearly the same thing as

K = 1
while K <= 5
  something
  K = K + 1;
end

But sometimes you do not need to count. For example,

   err = inf;
   while abs(err) > 0.1
     some calculation
     err = something
   end